The present invention, in some embodiments thereof, relates to fluid flow and, more particularly, but not exclusively, to a method and system for synchronizing fluidic actuators.
Fluid flow separation can occur when a compressible or incompressible fluid flows over a surface, in particular a convex curved surface, such as an interior surface of a fluid conduit or an exterior surface of a body immersed in a fluid. Flow separation can occur under laminar or turbulent flow conditions, depending upon the boundary layer fluid flow characteristics and the geometry of the surface. It is often desirable to inhibit flow separation in order to reduce form drag or in order to increase aerodynamic lift. In general, the farther along a curved surface that a fluid travels before separation, the lower the resulting form drag and the higher aerodynamic lift.
Flow control technology relates generally to the capability to alter flow properties relative to their natural tendencies by introduction of a constant or periodic excitation. Flow control systems can be categorized into Passive Flow Control (PFC) systems or Active Flow Control (AFC) systems. PFC systems provide substantially constant flow control, whereas AFC systems allow flow control to be selectively applied to a surface in contact with the fluid.
AFC systems are typically utilized to inhibit or delay separation of the fluid flow over the surface. Known AFC systems typically include actuators or actuator arrays for introducing or removing perturbations to the flow and altering the flow characteristics near the surface.
U.S. Pat. No. 7,055,541 discloses a suction and periodic excitation flow control mechanism. The mechanism includes: a jet of fluid at a controlled input pressure which is directed by control pressure gradient between two opposite ports at the sides of the jet. The mechanism also comprises a suction slot for allowing additional fluid to join the flow and create an amplified flow. An oscillating deflection device directs the amplified flow in two or more exit directions.
U.S. Published Application No. 20100193035 discloses an automatic mechanism to produce a fluid jet with an oscillating exit direction. The mechanism includes a conduit which conveys a flow of fluid, a feedback control tube terminating in two control ports connected to one another by the feedback tube, and means for varying the effective diameter of the feedback control tube.
U.S. Published Application No. 20100194142 discloses a technique for reducing aerodynamic drag on a body moving through a fluid. A flow generator is mounted adjacent a blunt rear edge of the body. The flow generator generates a flow which controls an external flow at an edge of the body, wherein the flow of air oscillates in a direction parallel to the blunt edge.